Follow up for H-Index: What if the
citations array is sorted in ascending order? Could you optimize your algorithm?
Hint:
- Expected runtime complexity is in O(log n) and the input is sorted.
Solution:
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| class Solution { | |
| public: | |
| void helper(vector<int>& citations, int left, int right, int& h){ | |
| if(left>right) | |
| return; | |
| int m=(left+right)/2; | |
| int n=citations.size(); | |
| if(n-m == citations[m]){ | |
| h=citations[m]; | |
| return; | |
| } | |
| h = max(h, min(citations[m], n-m)); | |
| if(n-m>citations[m]) | |
| helper(citations, m+1, right, h); | |
| if(n-m<citations[m]) | |
| helper(citations, left, m-1, h); | |
| } | |
| int hIndex(vector<int>& citations) { | |
| int h=0; | |
| helper(citations, 0, citations.size()-1, h); | |
| return h; | |
| } | |
| }; |
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